1 Phy.I. II Fiance 4 ii 994) 1727-1735 OCTOBER 1994, PAGE 1727 Classification Phy,ncs Ah,i'iac"I 47.50 68.10 68.15 Dewetting of a water film between a solid and a viscoelastic liquid F. Brochard-Wyart PSI, Institut Curie, II rue P. et M Curie. 7~231 Paris Cedex 05, France (Rec.en.ed J2.lanuar>. J994, ieii.led J3 Ma>. J994, acc.ep'ed 6,lul_v1994) R4sum4. Un film d'eau dcrasd entre un wlide hydrophobe lS) et un poiymbre fondu (Pi est mdtastable, et ddmouille par nucldation et croissance de zones skche~ (rayon RI') au temps ') entourdes d'un bourrelet (qui collecte l'eau rejetdei. En tenant compte du comportement vi~co61astique de P, on est conduit h prddlre : al un rdglme purement dlastique si R < R~, oh le fondu a un comportement de caoutchouc, avec Rl'),'~" ; b) un rdgime vlsqueux, aux temps longs, oh le bourrelet est dtird par sa grande friction avec P, et se ddplace h vite~se constante. Abstract. A water film squeezed between a hydrophobic solid IS j and a polymer melt (Pi is meta~table and dewets by nucleation and growth of a dry patch (radius RI') at time ') surrounded by a rim (collecting the rejected water). Taking into account the viscoela~tic behaviour of P, we are led to predict a) a pure eta.i'ic. ie,qime if R < R~. where the melt behaves like a rubber, with RI t t~'~ b) a viscou~ regime, at longer times, where the rim is extended by it~ friction against P, and moves at con~tant velocity. 1. Introduction : dewetting of water films exposed to air, rubber, or viscoelastic liquids. The dewetting of liquid films has many practical applications. Current examples include ii the fast drying of glasses in di~h-washer~ induced by non-wettable chemical agents, iii the stability of the lacrimal film controlled by the proteins of tears (mucyn) in the case of liquid films exposed to air, iii) the aquaplaning of cars on wet roads, iv) the adhesion of flexible contact lenses to the cornea-protected by a water film, and vi the stability of films intercalated between a solid and a polymer melt (or two polymer melts) in polymer extrusion and coextrusion respectively. Ii A water film deposited on a hydrophobic surface, in air, is metastable, and nucleates dry patches [1-3], which grow with a constant velocity V =Cte56/ (0~«1) (1) ~~